Variable dust formation by the colliding-wind Wolf-Rayet system HD 36402 in the Large Magellanic Cloud

Infrared photometry of the probable triple WC4(+O?)+O8I: Wolf-Rayet system HD 36402 (= BAT99-38) in the Large Magellanic Cloud (LMC) shows emission characteristic of heated dust. The dust emission is variable on a time-scale of years, with a period near 4.7 yr, possibly associated with orbital motion of the O8 supergiant and the inner P ~ 3.03-d WC4+O binary. The phase of maximum dust emission is close to that of the X-ray minimum, consistent with both processes being tied to colliding wind effects in an elliptical binary orbit. It is evident that Wolf-Rayet dust formation occurs also in metal-poor environments.